Apple will cut off third-party app store updates if your iPhone leaves the EU for a month
To reflect the Digital Markets Act’s changes, users in the European Union are able to install alternative app marketplaces and install apps offered through alternative app marketplaces in iOS 17.4 or later. The country or region of your Apple ID must be set to one of the countries or regions of the European Union, and you must physically be located in the European Union.
Your device eligibility for alternative app marketplaces is determined using on-device processing with only an indicator of eligibility sent to Apple. To preserve your privacy, Apple does not collect your device’s location.
If you leave the European Union, you can continue to open and use apps that you previously installed from alternative app marketplaces. Alternative app marketplaces can continue updating those apps for up to 30 days after you leave the European Union, and you can continue using alternative app marketplaces to manage previously installed apps. However, you must be in the European Union to install alternative app marketplaces and new apps from alternative app marketplaces